To determine the effect of acute ethanol intoxication on the results of orthostatic tilt testing.Prospective, randomized crossover study. Subjects received ethanol (1.1 gm/kg) or an equal volume of water added to nonalcoholic beer. Orthostatic vital signs, ethanol concentration, and relative volume status were checked initially and hourly for 8 hours.Twenty healthy human volunteers, 10 men, and 10 women.Peak ethanol concentration was 116 +/- 18 mg/dL (mean +/- SD) 1 hour after ingestion. ANOVA for repeated measures revealed a significant difference in orthostatic pulse change and relative volume deficit between the ethanol and placebo groups (P < .05). Post hoc testing revealed significant differences between the two groups at two, five, seven and eight hours post ingestion for pulse change, and two to eight hours for volume status (Bonferroni's corrected t test, P < .0055). At 2 and 5 to 8 hours, there were significantly more positive tilt tests (+/- 30 beat/minute increase) in the ethanol group than in the placebo group (P < .05). Starting at 2 hours, the ethanol group had a statistically significant relative fluid deficit averaging .5 L by 3 hours. There was no difference in postural blood pressure changes between the two groups.In healthy volunteers, ethanol intoxication resulted in exaggerated postural pulse changes and in a greater proportion of positive orthostatic tilt test results than in a placebo group. These changes were accompanied by significant relative fluid deficits.